Search for the reactions e+e−→μ+τ− and e+e−→e+τ−

Abstract

We report on a search for the lepton-flavor-violating processes e + e − → μ + τ − and e + e − → e + τ − . The data sample corresponds to an integrated luminosity of 211 fb − 1 recorded by the BABAR experiment at the SLAC PEP-II asymmetric-energy B Factory at a center-of-mass energy of √ s = 10.58 GeV . We find no evidence for a signal and set the 90% confidence level upper limits on the cross sections to be σ μ τ < 3.8 fb and σ e τ < 9.2 fb . The ratio of the cross sections with respect to the dimuon cross section are measured to be σ μ τ / σ μ μ < 3.4 × 10 − 6 and σ e τ / σ μ μ < 8.2 × 10 − 6 .